Solve for $x$ and $y$ using substitution. ${6x-3y = 9}$ ${y = 5x+3}$
Since $y$ has already been solved for, substitute $5x+3$ for $y$ in the first equation. ${6x - 3}{(5x+3)}{= 9}$ Simplify and solve for $x$ $6x-15x - 9 = 9$ $-9x-9 = 9$ $-9x-9{+9} = 9{+9}$ $-9x = 18$ $\dfrac{-9x}{{-9}} = \dfrac{18}{{-9}}$ ${x = -2}$ Now that you know ${x = -2}$ , plug it back into $\thinspace {y = 5x+3}\thinspace$ to find $y$ ${y = 5}{(-2)}{ + 3}$ $y = -10 + 3$ $y = -7$ You can also plug ${x = -2}$ into $\thinspace {6x-3y = 9}\thinspace$ and get the same answer for $y$ : ${6}{(-2)}{ - 3y = 9}$ ${y = -7}$